Aside from the pain of accidentally standing on the occasional discarded block, parents around the world have grown to appreciate LEGO as an innocent distraction for generations of children.

However, the small plastic blocks are not as innocent as they used to be, according to New Zealand research out Monday -- in fact, they're increasingly violent.

Researchers at the University of Canterbury said the increasing violence was contrary to the Danish toymaker's policy that LEGO products aim to discourage pretend violence as a primary play incentive.

Lead author Dr Christoph Bartneck said the LEGO company had become the world's largest toy manufacturer and so researchers decided to test a new violence measurement tool on their products.

The designs were meant to enrich play with engaging conflict scenarios where aggression might be used for the purpose of overcoming imaginary evil.

"LEGO has been one of the few toys that have been around for a very long time with their basic system largely unchanged; bricks from the '70s still fit modern bricks. Hence it's an ideal product to investigate changes of violence in toys," Bartneck said in a statement.

"First, we analyzed the frequency of weapon bricks in LEGO sets. Their use has significantly increased and nearly 30 percent of today's LEGO sets include at least one weapon brick. Second, we empirically investigated the perceived violence in the LEGO product catalogues from the years 1978 to 2014."

The results of 161 participants rating hundreds of LEGO catalogue pages showed that the violence of the depicted products increased significantly over that time.

"The chances of observing violence in a LEGO catalogue pages has increased steadily by 19 percent per year," said Bartneck.

"Currently, around 40 percent of all pages contain some type of violence. In particular, scenarios involving shooting and threatening behavior have increased over the years. The atmosphere of the violent acts is predominantly perceived as exciting."

The LEGO Company's products were not as innocent as they used to be, Bartneck said.

"The LEGO company often claims that their violence normally happens within a humorous context, yet the results show that humorous is the least likely atmosphere. Material harm is the most frequent consequence of the violent acts followed by mild harm or injuries."